Moved the free case to top of MPgetlock and MPtrylock
Added some lock hit profiling.
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fsmp
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4fa08df3f6
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@ -27,6 +27,19 @@
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#include <i386/isa/intr_machdep.h>
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/*
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* GLPROFILE showed that the lock was found to be free approx. 16 times
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* more often that it was found to be already owned. FREE_FIRST forces
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* the code to look for a free lock before looking for an owned lock.
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owned: free: fail:
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_gethits: 118de 1c7dd3 3f106
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_tryhits: 9938 2196d 44cc
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*/
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#define FREE_FIRST
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#define GLPROFILE
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#define MAYBE_PUSHL_EAX pushl %eax
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#define MAYBE_POPL_EAX popl %eax
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@ -40,6 +53,47 @@
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NON_GPROF_ENTRY(MPgetlock)
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movl 4(%esp), %edx /* Get the address of the lock */
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#ifdef FREE_FIRST
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1:
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movl $FREE_LOCK, %eax /* Assume it's free */
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movl _cpu_lockid, %ecx /* - get pre-shifted logical cpu id */
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incl %ecx /* - new count is one */
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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jne 2f /* ...do not collect $200 */
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#ifdef GLPROFILE
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incl _gethits2
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#endif /* GLPROFILE */
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ret
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2:
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movl (%edx), %eax /* Try to see if we have it already */
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andl $COUNT_FIELD, %eax /* - get count */
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movl _cpu_lockid, %ecx /* - get pre-shifted logical cpu id */
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orl %ecx, %eax /* - combine them */
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movl %eax, %ecx
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incl %ecx /* - new count is one more */
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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#ifdef GLPROFILE
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jne 4f /* - miss */
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incl _gethits
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#else
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jne 3f /* - miss */
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#endif /* GLPROFILE */
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ret
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#ifdef GLPROFILE
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4:
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incl _gethits3
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#endif /* GLPROFILE */
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3:
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cmpl $FREE_LOCK, (%edx) /* Wait for it to become free */
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jne 3b
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jmp 1b /* XXX 1b ? */
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#else /* FREE_FIRST */
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1:
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movl (%edx), %eax /* Try to see if we have it already */
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andl $COUNT_FIELD, %eax /* - get count */
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@ -50,6 +104,9 @@ NON_GPROF_ENTRY(MPgetlock)
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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jne 2f /* - miss */
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#ifdef GLPROFILE
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incl _gethits
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#endif /* GLPROFILE */
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ret
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2:
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movl $FREE_LOCK, %eax /* Assume it's free */
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@ -57,13 +114,24 @@ NON_GPROF_ENTRY(MPgetlock)
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incl %ecx /* - new count is one */
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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je 4f /* ...do not collect $200 */
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#ifdef GLPROFILE
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jne 4f /* ...do not collect $200 */
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incl _gethits2
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#else
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jne 3f /* ...do not collect $200 */
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#endif /* GLPROFILE */
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ret
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#ifdef GLPROFILE
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4:
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incl _gethits3
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#endif /* GLPROFILE */
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3:
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cmpl $FREE_LOCK, (%edx) /* Wait for it to become free */
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jne 3b
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jmp 2b /* XXX 1b ? */
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4:
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ret
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#endif /* FREE_FIRST */
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/***********************************************************************
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* int MPtrylock(unsigned int *lock)
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@ -74,6 +142,44 @@ NON_GPROF_ENTRY(MPgetlock)
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NON_GPROF_ENTRY(MPtrylock)
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movl 4(%esp), %edx /* Get the address of the lock */
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#ifdef FREE_FIRST
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movl $FREE_LOCK, %eax /* Assume it's free */
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movl _cpu_lockid, %ecx /* - get pre-shifted logical cpu id */
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incl %ecx /* - new count is one */
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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jne 1f /* ...do not collect $200 */
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#ifdef GLPROFILE
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incl _tryhits2
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#endif /* GLPROFILE */
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movl $1, %eax
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ret
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1:
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movl (%edx), %eax /* Try to see if we have it already */
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andl $COUNT_FIELD, %eax /* - get count */
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movl _cpu_lockid, %ecx /* - get pre-shifted logical cpu id */
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orl %ecx, %eax /* - combine them */
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movl %eax, %ecx
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incl %ecx /* - new count is one more */
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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jne 2f /* - miss */
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#ifdef GLPROFILE
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incl _tryhits
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#endif /* GLPROFILE */
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movl $1, %eax
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ret
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2:
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#ifdef GLPROFILE
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incl _tryhits3
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#endif /* GLPROFILE */
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movl $0, %eax
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ret
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#else /* FREE_FIRST */
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movl (%edx), %eax /* Try to see if we have it already */
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andl $COUNT_FIELD, %eax /* - get count */
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movl _cpu_lockid, %ecx /* - get pre-shifted logical cpu id */
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@ -83,6 +189,9 @@ NON_GPROF_ENTRY(MPtrylock)
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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jne 1f /* - miss */
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#ifdef GLPROFILE
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incl _tryhits
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#endif /* GLPROFILE */
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movl $1, %eax
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ret
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1:
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@ -92,12 +201,21 @@ NON_GPROF_ENTRY(MPtrylock)
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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jne 2f /* ...do not collect $200 */
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#ifdef GLPROFILE
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incl _tryhits2
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#endif /* GLPROFILE */
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movl $1, %eax
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ret
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2:
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#ifdef GLPROFILE
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incl _tryhits3
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#endif /* GLPROFILE */
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movl $0, %eax
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ret
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#endif /* FREE_FIRST */
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/***********************************************************************
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* void MPrellock(unsigned int *lock)
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* ----------------------------------
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@ -264,3 +382,24 @@ NON_GPROF_ENTRY(rel_isrlock)
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.globl _mp_lock
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.align 4 /* mp_lock aligned on int boundary */
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_mp_lock: .long 0
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#ifdef GLPROFILE
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.globl _gethits
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_gethits:
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.long 0
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_gethits2:
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.long 0
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_gethits3:
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.long 0
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.globl _tryhits
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_tryhits:
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.long 0
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_tryhits2:
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.long 0
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_tryhits3:
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.long 0
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msg:
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.asciz "lock hits: 0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x, 0x%08x\n"
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#endif /* GLPROFILE */
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